How to Fix a Leaking Bathroom Faucet

A dripping faucet is one of those small annoyances that compounds. One drop per second adds up to 2,700 gallons wasted in a year, and the sound in a quiet bathroom becomes maddening. The good news: most leaks originate from the same worn parts, and replacing them is straightforward work that doesn't require a plumber's license or special tools. The leak is almost always happening inside the faucet body where moving parts meet rubber seals. Knowing where to look and what to swap out gets the job done fast.

1. Kill the pressure first. Locate the shut-off valves underneath the sink, typically two oval knobs attached to the supply lines. Turn both the hot and cold valves clockwise until they stop. Turn on the faucet to release any remaining water pressure in the lines.
2. Know your faucet model. Look at your faucet. Is it a single-handle, two-handle, or ceramic-cartridge design? Single-handle faucets usually have one knob or lever. Two-handle faucets have separate hot and cold knobs. Cartridge faucets often look modern and smooth with a single lever. This determines which parts you'll need to replace.
3. Expose the guts. For two-handle faucets, look for a small set screw or cap on the handle. If there's a decorative cap covering the base, gently pry it off with a flat screwdriver. Unscrew the handle screw with the appropriate screwdriver (usually Phillips or flathead). Lift the handle straight up and set it aside.
4. Loosen the locking nut. Below the handle sits a large hexagonal or decorative nut called the packing nut. Use an adjustable wrench or the correct socket size to turn it counterclockwise. This nut holds the cartridge or valve stem in place. Unscrew it fully and set it aside with the handle.
5. Extract the cartridge. Grasp the exposed valve stem or cartridge and pull it straight up with steady pressure. It may require a slight twisting motion as you pull. If it's stuck, apply penetrating oil and wait 10 minutes, then try again. Some cartridges require a special puller tool, which you can rent from a hardware store or buy for $10.
6. Swap the worn seals. Once the cartridge or stem is out, look at the rubber washers and O-rings. Worn washers are flat, cracked, or visibly degraded. If the parts look intact, the issue may be mineral buildup. Either way, replace all rubber seals with a kit designed for your faucet model. These kits typically cost $5 to $15 and include washers, O-rings, and springs.
7. Lubricate the seals. Before installing new O-rings, coat them lightly with silicone-based faucet grease (included in most repair kits or sold separately for $3). This helps them sit properly and seal without binding. Do not use petroleum jelly or all-purpose lubricant.
8. Seat the cartridge tight. Follow the reverse order of disassembly. Insert the new washers and springs first if they were separate components. Slide the cartridge or stem back into its housing, aligning it with the grooves or notch. Push it down firmly until it seats. The cartridge should not wobble.
9. Secure the packing nut. Screw the packing nut back down over the cartridge with your wrench, turning clockwise. Tighten it firmly by hand first, then use the wrench for a final snug turn. Do not overtighten—you need only enough pressure to hold the cartridge in place.
10. Restore the handle. Slide the handle back onto the stem, aligning the screw hole. Insert the handle screw and turn it clockwise with your screwdriver until snug. If there was a decorative cap, press it back into place until it clicks or sits flush.
11. Verify the fix works. Turn both shut-off valves counterclockwise slowly, starting with cold water. Open the faucet to let air out of the lines. Check for leaks around the base and under the sink. Turn the handle through its full range to ensure smooth operation. Let the water run for 30 seconds to confirm the leak is gone.
12. Caulk and seal. If water leaks around the faucet body where it meets the sink, apply a thin bead of waterproof silicone caulk around the base. Smooth it with a wet finger. Let it cure per the product instructions before using the sink.